Electric resistance furnace



2 Sheets-Sheet l INVENT'OR ATTORNEY Sept. 20, 1949. G. TURNER ELECTRIC RESISTANCE FURNACE Filed March 9, 194e WGA.

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Sept. 20, 1949. G. TURNER l ELECTRIC RESISTANCE FURNACE 2 Shee'gs-Sheet 2 Filed March 9, 1946 INVENTOR FIGA ATTORNEY Patented Sept. 20,4949

HoF/FICE ELECTRIC RESISTANCE FURNACE George Turner, Dudley, England Application March 9, 1946, Serial No. 653,272

In Great Britain March 29, 1945 7 Claims.

This invention relatesto electric furnaces and is applicable generally. One of the applications of the invention is the tunnel ovens andl kilns for pottery.

The object of the present invention is to provide an improved construction.

According to vthe present invention, one or more groups of electric rheating elements arranged on refractory supports spaced one above another are mounted within the sides of the furnace in such a manner that they or each group can be Withdrawn from the furnace through an opening in the upper part of the furnace structure.

Also according to the present invention, one or more groups of approximately horizontal bars are provided, the barsbeing supported in spaced relationship one above another by supporting members or portions disposed between the ends of adjacent bars, and electric heating elements in the form of coils are suspended on these bars,

the whole assembly, including the bars, coils and supporting members, being'removable as a unit by withdrawing it through an opening at the upper part of the furnace body,

The supporting members 'may rest each upon the one below it, and each may have a lateral opening receiving the end of an element-carrying bar.

The supporting members may each be pro-` vided with a recess anda projection at opposite sides, so that when they are superposed, the projection of one member engages in the recess of another member, whereby the members are retained in the requiredrelationship.

Further, the supporting members may be provided each with an opening extending from top to bottom, which openings` are in alignment when the assembly is complete, the arrangement being such that after assembly, rods may beinserted through these openings one at each side of the assembly, the rods'having heads or lateral projections at their lower ends which can be made to engage beneath the assembly so that the assembly can be lifted out bodily by lifting the rods upwardly.

'The side of the furnace for each assembly may be provided with a vertical recess of channel form, the sides of this. channel being pro vided with vertical or slightly inclined groovesto accommodate the edge portions of the assembly, and at the top the openingy through which the assembly can be withdrawn is closed during working by a removableA heat insulating block of material, y e Y e i scale than Figures 1 to 3.

Referring to the drawings- Figure 1 is a transverse section through a tunnel oven to whichV the invention has been applied.

Figure 2 is a plan viewrpartly in section.

Figure 3 is a sectional side View.

Figure 4 is a sectional plan.

Figure 5 isl a perspective view showing the component parts of the assembly.

Figures 4, 5, '7, and Sfare drawn to a larger Figure Gis a side viewf of animplement which can be employed'for drawing the assembly from the furnace. n y y y Figures 7 and 8 show alternative constructions for the component parts'shown in Figure 5.

In the construction illustrated, opposite sides of the furnace are formed by wblocks In provided with a series of vertical 'recesses II of channel form, the sides of these recesses having vertical grooves I2 of semi-circular section. At the inner sides of the blocks the'sdes of the recesses may diverge as shown at 9. f l Y At the rear of' thefurnace sides are disposed blocks 42, each having afoot 43 at its bottom and blocks 44 and 45, forming supporting means, resting on said foot and disposed at the bottom of the vertical recesses II. yThe outer sidesof the furnace comprise b19cks`r46 and the bottom of the furnace is ,built up of blocks 41 and 48.

Immediately above each of these recesses the roof I3 of the furnace is provided with a shouldered opening normally Aclosed by a removable block I4 of heat insulating material, the block being shouldered at I5 to correspond with the shoulders of the opening. The tops of these blocks may extendsomewhatrabove the top of the furnace structure, and they may be provided with recesses at opposite sides so that they can be handled conveniently.

The assemblies of supporting members and horizontal bars which carry the elements may be built up of a bottom-bar |51, having parallel side faces I1 and rounded ends I8 of semi-circular section. These bars are, adapted to slide downwardly into the recesses inthe furnace walls with the ends of the l'bars engaging in the grooves I2 provided in the sides of the'recess. When the bars are ,inA position, the back of the recess ll,-which,r,n z-tyl be nat, is spaced away from the rear side of the bar.

Superposed on ythe ends` of the bar are two piles of supporting ,blocksr I9. Each of these blocks may be rof cylindrical! form having va square recess 20 at the tcpand a square projection 2i of slightly smaller dimensions at the bottom, so that when the supporting members are erected one upon another, they interengage and are thus definitely positioned in relation to each other.

Further, at one side of each block and at the lower end thereof, there is provided a partcylindrical recess 22.

Further, extending vaxially from the centre to the bottom, each of these supporting blocks and also the bottom bar is provided with a rectangular section hole 23. The upper side or the bottoni bar is provided with square recesses 2li. for receiving the square projections 2l at the lower sides of the two lowest supporting blocks.

The openings through the bottom bar conirnunicate with recesses 25 in the under side of the bar which may be of circular form of a diameter equal to the diagonal of the rectangular section hole 23.

The supporting blocks are provided with the part-cylindrical lateral recesses 22, and these recesses receive the ends of insulating tubes or bars 2S which carry the heating elements 2. The recesses 22 if desired may be omitted from the two blocks which are placed on the bottom bar. Each oi the tubes or bars, except the lowest one, may carry a collar 28 at the centre.

At the top of the assembly is a top bar 29 of similar form to the bottom bar, except that its upper surface is without the square recesses and the lower surface is provided with square projections 2l to engage the recesses 20, and this bar is provided intermediate its ends with two vertical holes Sli through which the Wire forming he heating element passes.

The heating element may be made in one ccntinuous length and is wound helically upon the horizontal bars or tubes, there being a winding Si on each side of the central collar 28, and the ends of the helical windings on each bar passing downwardly to the winding on the next bar below. The central collar is omitted from the lowest bar as the helical winding :on that bar is continuous instead of being separated into two lengths.

Alternatively, two heating elements may be accommodated on a single assembly, the elements being arranged either side by side or one above the other, in which case the leads of the individual elements would be insulated from each other by beads or the like.

The diameter of the helical windings 3i is greater than the diameter of the bars upon which they are suspended.

Two implements 32 are provided for use in inserting and withdrawing the assembly. These implements incorporate rods which may be of round or other section, and they are provided with T heads 33 at the bottom, the arrangement being such that they can be inserted from above and then given a part turn so that the heads engage the shoulders 34 formed in the bottom bar between the circular recesses 25 and the rectangular holes y23 therein. I

rI'he ends of the top and bottom bars are of semi-circular shape in plan so that the whole assembly is a sliding 'fit in the grooves at the sides of the channel-shaped recesses in the furnace side, and the inner side ofthe assembly is spaced away from the back of the channel.

Either the bottom bar H3 or the top bar 2Q may be made in sections as indicated in Figure '7 'or Figure 8 comprising two end sections 4o and an intermediate section 4l, the arrangement being such that the sections interlock 'at their ends, and

4 when the assembly is lifted, the two end sections of the sectional bar or bars support the intermediate section.

What I claim then is:

1. In an electric furnace, a furnace chamber having sides and a roof, said roof having an opening, a removable block in said opening, guides in the furnace side and disposed directly under said roof opening, a block at the rear of the furnace side, a foot at the bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, a bottom bar engaging said guides and resting on said supporting means, two spaced piles of vertically aligned supporting blocks resting on said bottom bar, each of said supporting blocks having opposed vertically spaced respective upper and lower end faces, the upper end face of each block having a recess therein, the lower end face of each block having a corresponding projection, whereby said blocks may interengage and be self-locating in superposed relationship, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles oi blocks may engage with said bottom bar, insulating bars extending between and having their ends supported by said blocks, resistance heating elements on said bars, and a top bar having at each end of its under face a projection, said projections each engaging in the recess in the upper block of each pile of blocks, said top bar, supporting blocks and bottom bar having aligned openings, whereby the assembly can be inserted and removed through the roof opening by inserting a headed tool through said aligned openings.

2. In an electric furnace, a furnace chamber having sides and a roof, said roof having a plurality of openings, a removable block in each of said openings, guides in the furnace side and disposed directly under each of said roof openings, a block at the rear of the furnace side, a foot at the bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom o'f said guides, a bottom bar engaging said guides and resting on said supporting means, two spaced piles of vertically aligned supporting blocks resting on said bottom bar, each of said supporting blocks having opposed vertically spaced respective upper and lower end faces, the upper end face of each block having a recess therein, the lower end face of each block having a corresponding projection, whereby said blocks may interengage and be lself-locating in superposed relationship, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles of blocks may engage.

with said bottom bar, insulating bars extending between and having their ends supported by said blocks, resistance heating elements on said bars, and a top bar having at each end of its under face a projection, said projections each engaging in the recess in the upper block of each pile of blocks, said top bar,supporting blocks and bottom bar having aligned openings, whereby the assembly can be inserted and removed through each of the roof openings by inserting a headed tool through said aligned openings.

3. In an electric furnace, a furnace chamber having sides and a roof, said'roof having an opening, a removable block in said opening, guides in the furnace side and disposed directly under said roof opening, a blockat the rear of the furnace side, a foot lat the bottom Avof said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, a botallegareL tombarfengaging said guidesandresting on said supporting means, two spacedipiles of vertically aligned supporting blocks resting on v,said bottom bar, each. of said supporting blocks having opposed ;,vertically spaced ,respective ,upper and lowerend faces, vthe upper.. end face of each block having a recess therein, the lower end face of each blockk having 1a corresponding projection whereby said blocks may interengage and be self-locating in `superposed relationship, said recess and projections beingnon-circular so that said blocks are positively locat'edwith respect to each other, each end of the upper face of saidbottom bar having a similar recess formed therein, whereby said piles of blocks mayengage with saidbottom bar, insulating y'bars extending `between and having their ends supported by saidA blocks, resistance heating elements on said bars, and a top bar havingat each end ofv itsl under face aprojection, said projections each engagingin the recess in the upper .block` of each pilerof blocks, said topV bar, supporting blocks and bottom bar having aligned openings, whereby the assembly can be inserted and yremoved through the roof opening by inserting a headed tool through Said aligned openings.

4. In an electric furnace, a furnace chamber having sides and a roof, said roof having an opening, aremovable block in said opening, guides in the furnace side and disposed directly under said roof opening, a Vblock at Uthe rear of the furnace side, a foot at thev bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, a bottom bar engaging said guides and resting on said supporting means, two spaced piles of vertically aligned supporting blocks resting on said bottom bar, each of said supporting blocks having opposed vertically spaced respective upper and lower end faces, the upper end face of each block having a recess therein, the lower end face of each block having a corresponding projection, whereby said blocks may interengage and be self-locating in superposed relationship, said recesses and projections being non-circular so that said blocks are positively located with respect to each other, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles of blocks may engage with said bottom bar, said supporting blocks having recesses in their sides, insulating bars extending between the piles of supporting blocks and having their ends located in said recesses, all of said bars, except the lowest, having a washer mounted thereon at a position intermediate its ends, a continuous heating element having helical windings on the bars at each side of each of said washers, and having a helical winding on the lowest bar, and a top bar having at each end of its under face a projection, said projections each engaging in the recess in the upper block of each pile of blocks, said top bar, supporting blocks and bottom bar having aligned openings, whereby the assembly can be inserted and removed through the roof opening by inserting a headed tool through said aligned openings.

5. In an electric furnace, a furnace chamber having sides and a roof, said roof having an opening, a removable block in said opening, guides in the furnace side and disposed directly under said roof opening, a block at the rear of the furnace side, a foot at the bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, said furnace side being formed by blocks having vertical recesses and said guides being formed by grooves inthe sides of saidrvvertica'l recesses, a bottom .bar engaging said guides and restingfon said supporting means, two spaced piles of vertically aligned supporting blocks resting on said bottom bar,` each of ysaid supporting blocks having opposed vertically spaced respective upper and lowerend faces, the upper end face offeach blockhaving a recess therein, the lower end face of each block havinga corresponding projection, whereby said blocks may interengage and be selflocating in superposed relationship, said recesses and projections being non-circular so that said blocks are positively located with respect to each other, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles of blocks may engage with said bottom bar, said supporting blocks having recesses in their sides, insulating bars extending between the piles of supporting blocks and having their ends located in said recesses, all of said bars, except the lowest, having a washer mounted thereon at a position intermediate its ends, a continuous: heating element having helical winding on the bars at each side of each of said washers, and having a helical winding on the lowest bar, and a top bar having at each end of its under face a projection, said projection each engaging in the recess in the upper block of each pile of blocks, said top barsupporting blocks and bottom bar havingaligned openings, whereby ythe assembly can be inserted and removed through the roof` opening by inserting a headed tool through said aligned openings.

6. In an electric furnace, a furnace chamber having sides and a roof, said roof having an opening, a removable block in said opening, guides in the furnace side and disposed directly under said roof opening, a block at the rear of the furnace side, a foot at the bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, said furnace side being formed by blocks having vertical recesses and said guides being formed by grooves spaced from the back of said recesses, a bottom bar engaging said guides and resting on said supporting means, said bottom bar being spaced away from the back of said recesses, two spaced piles of vertically aligned supporting blocks resting on said bottom bar, each of said supporting blocks having opposed vertically spaced respective upper and lower end faces, the upper end face of each block having a recess therein, the lower end face of each block having a corresponding projection, whereby said blocks may interengage and be self-locating in superposed relationship, said recesses and projections being non-circular so that said blocks are positively located with respect to each other, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles of blocks may engage with said bottom bar, said supporting blocks having recesses in their sides, insulating bars extending between the piles of supporting blocks and having their ends located in said recesses, all of said bars, except the lowest, having a washer mounted thereon at a position intermediate its ends, a continuous heating element having helical windings on the bars at each side of each of said washers, and having a helical, winding on the lowest bar, and a top bar having at each end of its under face a projection, said projections each engaging in the recess in the upper block of each pile of blocks, said top bar, supporting blocks and bottom bar having aligned openings, whereby the assembly can be inserted 7 and removed through the roof opening by inserting a headed tool through said aligned openings,

7. In an electric furnace, a furnace chamber having sides and a roof, said roof having an opening, a removable block in said opening, guides in the furnace side and disposed directly under said roof opening, a block at the rear oi the furnace side, a foot at the bottom of said block and blocks forming supporting means resting on said foot and disposed at the bottom of said guides, a bottom bar engaging said .guides and resting on said supporting means, two spaced piles of vertically aligned vsupporting blocks resting on said bot*- toin bar, each of said supporting blocks having opposed vertically spaced respective upper and lower end faces, the upper end face of each block having a recess therein and the lower end face of each block having a corresponding projection, whereby said blocks may interengage and be selflocating in superposed relationship, lsaid recesses and projections being non-circular so that said blocks `are .positively located with respect to each other, each end of the upper face of said bottom bar having a similar recess formed therein, whereby said piles of blocks .may engage With -said bottom bar, insulating bars extending between and having their ends supported by said blocks, resistance heating elements on said bars, and a top `bar having at each `end of its under f ace a projection, said projections each engaging in the recess in the upper block of each pile of blocks, said top bar, supporting blocks and bottom bar having aligned openings, said aligned openings being of elongated section, said bottom bar having recesses of circular section in its lower side communicating with the openings in said bottom bar, wherein the assembly can be inserted and removed throughthe roof opening by inserting a headed tool through said aligned openings.

GEORGE TURNER.

REFERENCES CITED The following references are of record in the le of this patenti UNITED STATES PA'IEN'rs Number Name Date 1,057,745 Kohn Apr. 1, 1913 1,495,503 Armstrong May 27, 1924 1,533,224 Colby Apr. 14, 1925 1,535,547 Reid Apr. 28, 1925 1,572,881 Brace Feb. 16, 1926 1,611,754- Keenan Sept. 6, 1927 1,673,543 Wirz June 12, 1928 1,889,362 'Hogel Nov. 29, 1932 FOREIGN PATENTS Number Country Date 270,035 Great Britain May 5, 1927 648,331 France Aug. 13, 1928 125,169

vA1-istria Oct. 26, 1931 

